Analysis of the Process of Thread Movement During Its Unwinding from the Packages of Sewing and Knitting Machines

The article addresses the topical issue of finding the thread speed and tension fluctuations when winding it from bobbin in sewing equipment, which is important for the subsequent calculation of the technological parameters of product development. The purpose of the research was an analytical and practical study of the process of moving a section of thread along a complex trajectory, taking into account the movement of the thread retractor. Analytical methods used in the theory of mechanisms and machines, as well as mathematical modeling, were applied. Experimental studies have been carried out to confirm the theoretical results obtained in production conditions. The results of analytical modeling of the movement and velocity of the thread segment are presented, and the nature of the self-oscillating movement of the thread is determined. The mathematical dependences of the change in the speed of the thread section on the physical and mechanical properties of the threads, the design parameters of the equipment and speed modes are determined. The findings can be used in practical calculations of the speed regimes in sewing and knitting machines during the design of complex structure products.